The inventive concept relates to three-dimensional semiconductor memory devices and to methods of fabricating the same. In particular, the inventive concept relates to semiconductor devices having a three-dimensional arrangement of memory cells and to methods of fabricating the same.
Techniques aimed at increasing the capacity of an electronic memory device include (1) pattern miniaturization and (2) multi-level cell (MLC) techniques. However, pattern miniaturization entails relatively expensive manufacturing processes; and the overall memory capacity that can be attained by employing an MLC technique is limited because only a certain number of bits can be stored in each cell fabricated using the technique. 3D-IC memory techniques have also been developed with an aim towards increasing memory capacity. A 3D-IC memory technique generally refers to any technique of arranging memory cells three-dimensionally. Thus, a 3D-IC technique may be used in combination with pattern miniaturization and MLC techniques to realize even greater memory capacities.
One 3D-IC technique, of arranging memory cells three-dimensionally, is a punch-and-plug technique. The punch-and-plug technique includes sequentially forming multiple thin layers on a substrate and then forming plugs through the thin layers. This technique allows for a three-dimensional memory device to be realized without incurring relatively high manufacturing costs.